A filter assembly for filtering a fluid is known from a variety of applications including hydraulic systems, fuel systems and engine lubrication systems. The filter assembly is provided with a replaceable filter element that can be accommodated in a filter housing. The filter housing is removably connected to a head, for example by screwing. The head has an inlet and an outlet. The fluid flows into the inlet of the head into the filter housing, passes through the filter element and flows out from the outlet of the head, so that any foreign material and the like within the fluid is caught and removed by the filter element as the fluid passes through the filter element.
The fluid to be filtered may enter the annular space between the filter element and the housing via the inlet in the head, after which the fluid is distributed along the outer circumferential surface of the filter element. The fluid then flows radially inward through the filter element whereby contaminants in the fluid are captured by the filter element. The filtered fluid subsequently flows to the outlet of the head. Alternatively, the flow may be reversed i.e. the contaminated fluid enters the interior of the filter element and is then forced through the filter element, thereby flowing substantially radially outward.
With use, the filter element undergoes gradual degradation of its performance due to clogging. The filter element may become clogged to the extent that it causes a problem in the hydraulic system, such as inadequate flow to components downstream of the filter, excessive pressures upstream of the filter element, and/or damage to the filter element allowing the accumulated contaminants to flow to components downstream of the filter element. This can be avoided by periodic replacement of the filter element or after the need for replacement has been brought to the attention of an operator of the system. Thus, the filter element of the filter assembly is replaced regularly.
The filter element is locked within the filter housing in operation. When replacing the filter element by a new filter element, the filter housing is disassembled from the head and the filter element is removed. This can be relatively difficult and also there are problems that arise with respect to environmental concerns. Nowadays, according to prior art, the filter element stays attached to the head when the filter housing is removed from the head. Only after removing the filter housing, the filter element can be disconnected and removed from the head. Taking into account the length of the filter element and housing this obviously requires a large removal height. Under the housing a free space of approximately the axial length of the filter element is required in order to be able to remove the housing. After removing the housing, subsequent removal of the filter element from the head is hindered by the filter element being wet and slippery from oil whilst large forces are required for removing the (still attached) filter element from the head. Removal or displacement of the filter element thus is complicated. A further disadvantage of the filter element initially staying attached to the head is that oil drips from the filter element onto a machine or floor below it.